Current systems of training for golfers are many and various. Some are purely mechanical, and help to train the user in technique by guiding the club into a motion thought to be preferable to achieve good results. Others measure some aspect of the player's performance during practice, and provide information which the player can use to improve their swing.
Many different schemes have been proposed for measuring and analysing various aspects of a golf swing. The depth of the analysis provided varies from a simple speed indicator to complex 3-dimensional motion and/or video analysis.
Speed indicators are typically either free-standing or attach to, or form part of, the club. Free standing indicators typically employ a sensor arrangement that uses magnetic forces, light beams or microwave radar to measure club activity and motion. More complex methods use gyroscopes and multi-axis accelerometers or video cameras/recorders connected to a computer for analysis.
Radar and light/laser devices are typically expensive, obtrusive, inaccurate, and can be difficult to set up. In the case of the radar devices, the point of measurement is not well defined. As the speed of, and therefore distance traveled by, the ball is dependent on the speed of the club head at impact, measurements at other times are not useful in this respect. Radar and laser devices also only produce speed information, which is, by itself, insufficient. More complex methods produce detailed results, but these require considerable skill and/or expertise to interpret, and so are not useful to the majority of golfers.
Speed measuring devices exist, such as that disclosed in U.S. Pat. No. 3,815,427, which fix to the club typically use one or more accelerometers to derive club head speed indirectly, by combining centripetal acceleration with radius of curvature. However these tend to be inaccurate for a number of reasons.
Firstly, they do not properly take into account the radius of curvature of the swing at the point of impact. Secondly, if the device is not attached close to the club head, then accurate measurement will not be possible. One reason for this difficulty is the inability to take account of shaft flexion. All these problems may be overcome by building the device into the head of the club, but this is expensive and very inconvenient.
Some methods require knowledge of properties of the equipment, such as the weight of the club head, and/or the ball. Furthermore, none of the systems or devices known to the applicant take into account the slowing distance of the club (the distance traveled by the club head between reaching peak speed and the instant of impact with the ball) which clearly affects the accuracy of any measurements provided.